The background description provided herein is for the purpose of generally presenting the context of the disclosure. Work of the presently named inventor, to the extent it is described in this background section, as well as aspects of the description that may not otherwise qualify as prior art at the time of filing, are neither expressly nor impliedly admitted as prior art against the present disclosure.
A color printer typically implements a multiple-color process to reproduce an image in color. For example, a four-color process generally includes the use of four color planes including inks (or toners) of cyan (C), magenta (M), yellow (Y), and key (K), and a six-color process generally adds orange and green to the traditional CMYK inks. During printing of a color image, a mechanical misalignment (or misregistration) of color planes within a printing mechanism can occur. A misalignment of color planes can cause noticeable artifacts such as a halo or white gap in a printed image.
Color trapping is a method for minimizing artifacts caused by a mechanical misalignment of color planes in a printing mechanism. Color trapping typically involves expanding lighter color regions, so that the lighter color regions are “trapped” under darker-colored regions along color edges. This trapping can reduce or eliminate the perceived image quality degradation associated with misregistration of color planes within a printing mechanism.
FIGS. 1a, 1b, 1c, and 1d illustrate the concepts of color trapping. FIG. 1a shows two regions A and B of different color planes that are to be printed adjacent each other. The boundary 102 between the two regions is referred to as a color edge.
FIG. 1b shows how regions A and B might appear if the color plane associated with region B suffers from horizontal misalignment. Because of the misalignment, a very visible gap 104 may appear between the two color regions.
FIG. 1c shows the results of color trapping in the situation in which there is no relative misalignment of color planes. Region A has been grown to extend into region B, resulting in an overlapping region 106. The color trapping is typically performed so that the overlapping region 106 is not noticeable or only minimally noticeable, by expanding light color regions into darker color regions. This minimizes the visual impact of the trapping, taking advantage of the fact that a lighter color is typically dominated by any overlying darker color.
FIG. 1d shows the result of color trapping in the situation where the toner plane associated with region B suffers from the same horizontal misalignment as illustrated in FIG. 1b. In this case, the gap between the two regions does not occur because of the color trapping. Depending on the degree of misalignment, some portion of the overlap 106 may or may not remain.